Today: Facebook, Twitter and Silicon Valley's other social-media stocks take another hit ahead of a trio of important earnings reports this week. Also: Apple and other traditional valley powerhouses gain while newer tech companies suffer on Wall Street.

Twitter has shown off tremendous revenue growth -- sales more than doubled in 2013, the fifth-best performance from a public Silicon Valley technology company -- but it has had trouble increasing its user base: The Wall Street Journal pointed out Monday that Twitter aimed to have 400 million engaged users at the end of 2013, but ended up with 241 million. Twitter's varied results in different metrics have made it a polarizing topic among financial analysts; Reuters noted that 11 analysts it tracks rate the stock a "Sell," while seven call it a "Buy," a much bigger split than other social stocks.

Twitter "needs to prove two things: that it can successfully increase its reach with advertisers; and that it can successfully increase its user base and engagement levels," Mahaney added.

Twitter will be followed by two other social companies that have dived more than 40 percent from their 52-week highs. Yelp arrives Wednesday, after the biggest decline in the group: The San Francisco online-reviews company is down 45.4 percent from its peak price of more than $100, after Monday's 3.6 percent decline to $55.55.

On Thursday, LinkedIn will take center stage, with expectations that revenue growth will continue to be a strength. Even with those expectations, though, the Mountain View professional-networking service has plunged 42.5 percent from an all-time high reached last year, after a 6.4 percent decline to $148.06 Monday.

Analysts and investors will be watching these reports sharply for signs that recent declines have more to with the investors than the companies, or the opposite.

"Given the sharp sell-off of many high growth technology stocks over the past 6 weeks, the upcoming Q1 earnings reports should determine whether a further decline is warranted due to deteriorating fundamentals ... or is more of a valuation correction and profit-taking activity," Wunderlich Securities analyst Blake Harper predicted in a note Monday.

Other traditional tech powerhouses with large influence on the SV150 also commanded price increases Monday, as Hewlett-Packard rose 1.9 percent to $32.19 and Oracle gained 1.7 percent to $40.13. However, two-thirds of the SV150 companies declined Monday on Wall Street, and entire sectors of smaller-cap companies were hit hard by investors, namely streaming media and cloud software. Silicon Valley's biggest names in streaming media, Netflix and Pandora Media, fell 2.4 percent and 2.9 percent respectively, as big tech companies continued to show off their Netflix rivals and Pandora's earnings continued to be parsed. In cloud software, Salesforce had the second largest percentage decline Monday in the SV150, diving 7 percent to $49.13, while NetSuite fell 4.5 percent to $73.59 before getting an after-hours boost from its earnings report.

And the widely watched Standard & Poor's 500 index: Up 6.03, or 0.32 percent, to 1,869.43

Check in weekday afternoons for the 60-Second Business Break, a summary of news from Mercury News staff writers, The Associated Press, Bloomberg News and other wire services. Contact Jeremy C. Owens at 408-920-5876; follow him at Twitter.com/jowens510.